The Effects of Structural Stiffness in Vibration Transmission Paths on Friction-Induced Vibration

Abstract

Research and /or Engineering Questions/Objective: Friction-induced vibration is a common phenomenon on the frictional contact interface between two solids in relative motion, which can be observed in many mechanical applications, especially for the brake system. The friction-induced vibration originated from the friction interface can transmit through the rigid connection structure of mechanical system and forms a vibration transmission path. The vibration transmission path, mainly reflected by the natural frequency and the damping ratio, influences the friction-induced vibration of system, even under the same friction interface. However, there is limited report on the friction-induced vibration of mechanical system under different vibration transmission paths. Therefore, the effect of structural stiffness in vibration transmission path on friction-induced vibration is investigated and discussed. Methodology: The friction tests are carried out on a small-scale tribometer, which achieves a frictional contact between the balls and disc samples. The structural stiffness of vibration transmission paths is reflected by different fixtures of samples, whose dynamic characteristics are tested by the hammer method. In addition, a detailed three-dimensional finite element model based on different structural stiffness in vibration transmission paths is established to simulate the experimental process. At last, a four-degree-of-freedom friction-induced vibration model, including the interaction between the structure characteristics and the friction interface, is established to investigate the influence of the vibration transmission paths on the system stability. Results: The instability of the friction system decreases with the increasing structural stiffness in vibration transmission path. However, when the structural stiffness exceeds the critical value, the instability of friction system is excited again, accompanied by severe friction-induced vibration and high frequency squeal noise. Similarly, the wear morphology is also influenced by vibration transmission paths. The higher structural stiffness is, the better tribological behavior of the contact interface is displayed. Once the critical stiffness is exceeded, more complicated tribological behavior of the contact interface is shown. Limitations of this study: Applying the findings to practice system is still under studied since a real friction system is much more complex comparing to the customized small-scale tribometer.What does the paper offer that is new in the field in comparison to other works of the author: The effect of structural stiffness in vibration transmission path on friction-induced vibration is investigated. The conclusions obtained by experimentally and numerically are beneficial for understanding the effect of structural stiffness in vibration transmission path on stability, vibration response and tribological behavior of the friction system. Conclusion: The results show that the stability and vibration response of the friction system is significantly affected by vibration transmission paths. Evaluating and eliminating the influence of vibration transmission path on the friction-induced vibration is extremely crucial and meaningful for investigating the generation mechanism of the friction-induced vibration more precisely.